Artificial contractile structure (1) for a medical device, said artificial contractile structure (3) comprising: - an elongated member (3) adapted to contact a hollow body organ； - a closure (9) adapted to form the artificial contractile structure (1) into a closed loop around said hollow body organ； - a tension system (11) arranged to be connected to a control unit (28), said tension system (1) being adapted to modify an internal diameter of said closed loop in response to a force applied by said control unit (28). According to the invention, said elongated member (3) comprises a resilient core (5) and a biocompatible outer sheath (7). Said tension system (11) furthermore comprises a first tensile element (13) attached to a first point (3c) of said elongated member, and a second tensile element (15) attached to a second point (3d) of said elongated member, each of said tensile elements (15, 17) passing through an adaptor (17) situated between said first point (3c) and said second point (3d).
